Which weathering process is most influenced by living organisms?

Biological weathering is the process most influenced by living organisms, which include plants, animals, fungi, and bacteria. These organisms contribute to the breakdown of rocks and minerals in a variety of ways. For example, the roots of plants can grow into cracks in rocks, exerting pressure as they expand and eventually breaking the rock apart. Additionally, certain microorganisms can secrete acids that chemically alter minerals, contributing to the weathering process.

Through biological activities, such as the burrowing of animals and the growth of lichens or moss on surfaces, biological weathering facilitates both physical disintegration and chemical alteration of rocks. This interplay emphasizes the essential role living organisms play in shaping the Earth's surface.

Other types of weathering, such as chemical and physical weathering, do involve some interaction with biological factors but are not primarily defined by them. Chemical weathering focuses on the alterations of minerals due to chemical reactions, while physical weathering involves mechanical processes that break down rocks without altering their chemical composition. Mechanical weathering specifically emphasizes the physical forces at work, such as freeze-thaw cycles and abrasion. Thus, the unique influence of living organisms clearly identifies biological weathering as the correct answer.